Method of manufacturing thick walled pressure vessels by electrical welding



June 21, 1932.

R. STRESA ANUFACTURING THI CK WALLED PRESSURE WELDING 29 METHOD 0 V ELS BY ELECTRICAL Filed Feb. l2, l9

INVENTOR. )P/C/MRD STRESAU ATTORNEY.

Patented June 21, 1932 UNITED STATES PATENT OFFICE RICHARD STRESAU, OF WAUWATOSA, WISCONSIN, ASSIGNOR TO A. 0. SMITH CORPOB.

" TION, OF MILWAUKEE, WISCONSIN, A CORPORATION OF NEW YORK METHOD OF MANUFACTURING THICK WALLED PRESSURE VESSELS BY ELECTRICAL WELDING Application filed February 12, 1929. Serial No. 389,292.

This invention relates to electrical welding of thick walled pressure vessels, and certain features thereof have particular application to the manufacture of pressure vessels such as the one disclosed in Patent Reissue No. 16,865 to L. R. Smith.

The object of the invention is to provide a novel method whereby such a pressure vessel may be more readily and economically manum factured.

The invention will be more readily understood by reference to the accompanying drawing in which:

Figure 1 is a perspective view of a thick 15 metal plate prepared for incorporation into the vessel.

Fig. 2 is an end elevation showing a plurality ofsuch plates arranged preparatory to welding. Fig. 3 is an end elevation of the head prepared for welding. V f 1 Fig. 4 is a central longitudinal section showing the head in position to be welded onto the ends of the plates.

Fig. 5 is a perspective view of the vessel.

In the manufacture of pressure vessels by forming a plurality of thick plates into curved segments and arranging the segments side by side in a circle to provide a tubular structure having a plurality of longitudinal seams to be welded, difiiculty has been encountered in maintaining said plates in substantially circular arrangement during the welding operation so that the structure produced will havea truly circular contour. This is particularly true where the plates are of extreme thickness such as in the manufac-. ture of high pressure vessels having a wall from 2m 6 inches or more in thickness, as disclosed in the above identified patent.

The plates 1 may be chamfcred while fiat and then formedinto curved segments by means of a pressing operation, or in any other suitable way. The segments are then arranged circumferentially on horizontally aligned spiders 2 and clamped in position thereon by any suitable means 3. The chamfered edges of the se ments are parallel and meet toprovide welding grooves in the respective seams for receiving deposited welding'metal from a fusible weldrod 4 which is fused into said seams by means of an electric are 5 established between the work and the weldrod.

In order to obtain a proper fusing and welding condition in any given welding groove, it is preferable to have said groove facing upwardly during the fusing opera tion. In the present invention the welding metal is fused into the top groove and then the spiders and plates are rotated to successively present the different grooves in position at the top for welding.

In the manufacture of the vessel it is preferable to employ five segments so as to "pro vide five seams 6, 7, 8, 9 and 10, to be welded.

After a layer of fusing welding metal has been deposited in groote 6, it is preferable to fuse metal into a groove as nearly opposite thereto as possible, such as either groove 8 or 9, since the stresses set up by the cooling of the deposited metal are in this way more uniformly distributed throughout the structure during the fabricating operation. employing five plates and providing five longitudinal seams to be welded, a definite sequence may be maintained throughout the fabricating operation, the welding being suc-v cessively applied to the difierent seams in the following order: 6, 9, 7, 10, 8, 6, 9, 7, 10, 8, etc. until the-welding grooves are completely filledand the fabrication of the structure is finished.

If only four plates-are employed and four longitudinal seams are, provided for welding, the welding operation is ordinarily transferred from the first seam to the seam opposite thereto and then to a seam between the same, and the stresses set up by such a sequence have a greater tendency to deform the structure during welding.

It has been found that the peculiar advantage given by the five seam construction is present when 3, 5, 7 S} or some larger odd number of seams is employed. By this method more uniform stress conditions are obsembled on the spiders, they may be rotated to present the grooves defined by their chamfered edges in any desired order. In some instances, it may be desirable to rotate the spiders step-by-step in one direction to present the grooves in succession, while in other cases the grooves may be presented in some predetermined order to meet welding conditions. 1

The manner in which the weld metal is deposited'in the grooves will depend upon the thickness of the plates and the results it is desired to obtain. Good results may be obtained by depositing the weld metal in layers.

If desired, the weld metal may be deposited from 'aflat plate'by spinning, pressin or other suitable means. It has been found difficult to form the head so that the edges thereof are truly circular. Consequently,

if the edges are chamfered prior to the forming operation, the lips 12 at theinner circumference of the edges may not be truly circular and may not properly align withthe lips 13 formed at the end of the tubular structure to provide a welding groove.

This difliculty ma be overcome by forming the head prior to t e chamfering operation and then 'chamfering the edge by a tool travelling in a truly-circular path. Inthis way the outer edge of the lip will betruly circular and will properly align with the lips provided on the end 'of the tubular structure irrespective of slight irregularities in the contour of the head.

However, since the edge of the head is not.

truly circular, the inner edge of the lips 12 -may be untrue causing a variation in thickness of the lips. In order to eliminate this, 1t is preferable to chamfer the inner side of the lips to cut the same to a true circular contour and thereby provide a lip of uniform thickness. It is also preferable to form the lips 13 in a similar manner after the tubular structure is fabricated to insure a perfect alignment of lips 12 and 13.

' he welding operation is preferably performed in the manner disclosed and claimed in my copending application, Serial No. 339,- 293, filed on even date herewith.

The lips 12 and 13 are preferably formed at or near the inner circumference of the edges to. provide the main welding groove 55 Having thus described the invention in desubstantially 0n the outer circumference of the vessel.

tail, I claim the various novel characteristics than three, of thick metal plates into curved I segments, arranging said segments in a circle and providing longitudinal welding grooves therebetween, fusing welding metal into one of said welding grooves to form a layervof deposited metal therein, fusing welding metal into a groove nearly opposite to said last specified groove to form a layer of deposited metal therein, successively fusing metal into nearly opposite non-fused grooves until all of the grooves have deposited metal fused therein, and repeating said fusing operation in similar sequence until the plates are welded into an integral tubular structure. 4

2.-In the manufacture of tubular structures, the steps comprising forming a number of thick metal plates into curved segments of equal radii, arranging said segments in a horizontal cylindrical formation and providing welding grooves longitudinally therebetween with one of said grooves positioned at the top of the structure, fusing welding metal v into said top groove to partially fill the same, then rotating the structure successively to position other welding grooves at the top for welding and fusing welding metal successively into said grooves to partially fill the same, and repeating similar successive welding operations in all of said grooves until the same are filled with successive Layers of deposited weld metal.

3. In the manufacture of tubular structure's, the steps comprising forn'iing a number, not less than five, of metal plates into curved segments of equal radii, arranging said segments in a cylindrical formation and providing welding grooves longitudinally therebetween with one of said grooves positioned at the top of the structure, fusing welding metal into said top groove to weld the plates adjacent thereto together, then retating the structure to position a groove nearly opposite to said last specified groove at the top for welding and fusing welding metal into said second specified groove to weld the plates adjacent thereto together, and continuing the successive operations of rotating'the structure and fusing weld metal into the respective grooves in similar sequence, passing from the groove last welded to one nearly opposite thereto, until all of said grooves are welded and an integral tubular structure is produced.

4. In the manufacture of tubular structures, the steps comprising forming a number, not less than three, of thick metal plates into curved segments of equal radii, arranging said segments in a horizontal cylindrical formation and providing welding grooves longitudinally therebetween with one of said z eeaiue grooves positioned at the top of the structure,

- fusing Welding metal into said top groove to partially fill the same, then rotating the structure successively to position each of the other welding grooves at the top for Welding and fusing Welding metal successively into each of said grooves to partially fill the same, and then repeating similar successive Welding operations until all of said grooves are filled With successive layers of deposited Weld metal.

5. The method of manufacturing thickwalled tubular structures, which comprises forming not less than three metal plates into complementary curved segments of equal radii, arranging said segments in a horizontal cylindrical formation and providing Welding grooves longitudinally therebetween With one of said grooves positioned at the top of the structure for Welding, fusing Welding metal into said top groove to partially fill the same then rotating the structure to position a groove nearly opposite to said last specified groove at the top for welding and g5 fusing Welding metal into said second specified groove to partially fill the same, successively rotating the structure and fusing metal into nearly opposite non-fused grooves until all of the grooves are partially filled with Weld metal, and repeating said rotating and fusing operations in similar sequence until the plates are Welded into an integral Weldin structure and the Welding grooves are fille with Welding metal.

In testimony whereof I have signed my name at Milwaukee, Wisconsin, this 8th day of February, 1929.

RICHARD STRESAU. 

